Too Much Taper Crimp?

[Walkalong]

Neck tension does the job on auto pistol calibers that headspace on the case mouth, the taper "crimp" is just there to completely remove the belling/flare. Too much can actually hurt neck tension, and your rounds will be "headspacing" off the extractor.

 

[Bill M.]

Thanks for that explanation. My problem seems to be too much belling from the Lee though the powder expansion die to move the powder measure all the way. It goes in too far. I guess I will try to adjust that again. Shooting my 9 mm in a Ruger single action revolver. Okay, I am re adjusted now and it all seems to be fine. I crimped and pulled a couple of bullets and am just barely getting a distortion of the bullet surface.

 

[rfwobbly]

What if you do put too much taper crimp on a thick plated bullet. Does it actually hurt anything? Mine distort the bullet just a little but the plating does not come off when I pull them. I think the pressure inside the case expands the case when the round is fired so I do not think there is a lot of "pull" on the plating.

Thick plated bullets can take it, but the vast majority of plated bullets on the market are thin plating, and you will break through the plating with improper crimp. We do not judge plating or crimp based on pulled bullets, but rather how they perform in the barrel. Plated bullets will shed their plating once the plating is fractured due to poor crimping practices. You can see it on the target paper. Looks like miniature shrapnel holes around the bullet hole.

Right now I fell better with a tight crimp because I have been reading for years and years how important a tight crimp is.

If we start with the concept that Taper Crimp is to erase the belling, then let's look at what happens when the belling is not properly erased.



So without proper TC there is no chambering. Therefore we could say that most of Taper Crimp's job is to satisfy the requirements of the chamber, not the cartridge. The chamber is like mamma, and "if mama ain't happy, then ain't no one gonna be happy".

So this "light taper crimp" and "heavy taper crimp" is a bunch of nonsense. There is only the small dimensional range that satisfies the needs of the chamber, and allows the cartridge to fully enter and properly head space. And that small dimensional range has measurements assigned to it, and can therefore be described best by numbers. Numbers that can be checked and then duplicated by more hard measurements.

"Tight taper crimp" means nothing. No one can duplicate it. In a lot of ways it's closest cousin is the teenager answering with the term "Whatever !"

 

[Jesse Heywood]

As stated, crimping jacketed bullets can be a lesson in futility. Why? The metal has to go somewhere. A taper crimp pushes the metal from the end to just below the crimp, which expands the neck diameter. This results in less neck tension. I have found that with taper crimp it is best to simply to crimp just enough to barely remove the bell in the neck.. This is where the Sheridan slotted gauge is helpful, allowing one to see where the metal moves.

 

[Lennyjoe]

I prefer a Lee factory crimp die for auto loader rounds. Revolver loads get a roll crimp.